The present invention relates to composite materials and methods of making same, and more particularly to composite materials including an addition polymer from an unsaturated monomer, and methods of making same.
Chemicals used in the electronics industry, among others, include chlorinated solvents such as 1,1,1-trichloroethane or methylene chloride, and inorganic acids, such as hydrofluoric acid and nitric acid. Accordingly, there is a need for protective clothing that will protect humans from contact with hazardous organic solvents, acids, and other chemicals.
Organic solvents of many varieties and characteristics are widely used by many industries. Many of these substances are readily absorbed through the intact skin. Widespread and profound biological dysfunctions can be produced by penetration of these substances into the body's metabolis systems. Such penetration generally occurs in two modes through any given protective material, by permeation and by breakthrough. Permeation occurs when the vapors as gaseous forms of a substance are able to pass through the protective material and become detectable on the opposite side of the membrane or material. Gaseous diffusion, therefore, delivers the substance to the skin interface, which must be protected. Once gaseous diffusion has occurred, the substance is free to penetrate and absorb through the skin barrier. Breakthrough occurs when a liquid form of a substance actually leaks through the protective material. Once through the material, the substance is then freely available for absorption through the intact skin.
Those concerned with the development of protective materials such as gloves have long recognized the need for protection and prevention of skin contact with toxic chemicals, including aqueous solutions, caustics, acids, and organic solvents, such as are used in the electronics industry. One of the most critical problems confronting designers of protective materials such as gloves has been protection and prevention of contact with toxic chemicals which is overcome by the present invention. Gloves of prior art materials such as latex and buna rubber have been found to quickly dissolve in chlorinated solvents or to otherwise not provide the desired protection in such situations. Much of the materials available are either dissolved or penetrated in minutes. This results in inadequate protection allowing chemicals to be absorbed into the body through the skin or damaging the skin itself. The present invention fulfills the need for improved protection against skin absorption and skin contact with such chemicals.
Polyethylene has long been recognized as a desirable polymer to contain many of these chemicals. Its hydrophobic nature resists wetting, particularly by aqueous solutions. One critical drawback, however, is the ability of solvent vapors to readily penetrate the polymer. Films of vinylidene chloride, polymers or copolymers (such as with vinyl chloride) of vinylidene chloride, or saran such as sold under the trademark "SARAN" have low permeation by gases and liquids, although their chemical resistance is not as good as polyethylene.
Presently available equipment, such as polyvinyl chloride (PVC) gloves or polyethylene gloves, either disintegrate when contacted by solvents (e.g., with PVC) or allow a significant amount of solvent vapor to penetrate (e.g., with polyethylene). Composite materials combining natural or synthetic rubbers with various fabrics are too cumbersome for delicate work and are expensive.
Polyurethane gloves are believed to provide protection against permeation and breakthrough from organic solvents, but not for caustics and acids.
U.S. Pat. No. 3,575,793 issued Apr. 20, 1971 to G. C. Paisley appears to teach a laminate of biaxially oriented polypropylene film to a cellophane film having, on at least the surface contacting the polypropylene, a coating of saran applied from a solvent solution. U.S. Pat. No. 3,274,004 issued Sept. 20, 1966 to H. Curler, et al. appears to teach a laminate of saran-coated cellophane between layers of polyethylene with an additional outside layer of oriented polypropylene film. Neither of these references appear to show lamination of an unsupported, preformed saran film to a polyolefin layer.